RDMA/rxe: Fix the failure of ibv_query_device() and ibv_query_device_ex() tests

RDMA/rxe: Fix the failure of ibv_query_device() and ibv_query_device_ex() tests

In rdma-core, the following failures appear.

"
$ ./build/bin/run_tests.py -k device
ssssssss....FF........s
======================================================================
FAIL: test_query_device (tests.test_device.DeviceTest.test_query_device)
Test ibv_query_device()
----------------------------------------------------------------------
Traceback (most recent call last):
   File "/home/ubuntu/rdma-core/tests/test_device.py", line 63, in
   test_query_device
     self.verify_device_attr(attr, dev)
   File "/home/ubuntu/rdma-core/tests/test_device.py", line 200, in
   verify_device_attr
     assert attr.sys_image_guid != 0
            ^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError

======================================================================
FAIL: test_query_device_ex (tests.test_device.DeviceTest.test_query_device_ex)
Test ibv_query_device_ex()
----------------------------------------------------------------------
Traceback (most recent call last):
   File "/home/ubuntu/rdma-core/tests/test_device.py", line 222, in
   test_query_device_ex
     self.verify_device_attr(attr_ex.orig_attr, dev)
   File "/home/ubuntu/rdma-core/tests/test_device.py", line 200, in
   verify_device_attr
     assert attr.sys_image_guid != 0
            ^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError
"

The root cause is: before a net device is set with rxe, this net device
is used to generate a sys_image_guid.

Fixes: 2ac5415022d1 ("RDMA/rxe: Remove the direct link to net_device")
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://patch.msgid.link/20250302215444.3742072-1-yanjun.zhu@linux.dev
Reviewed-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
Tested-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>